A repeat of last week's 0-0 draw in Poland could see the teams battle it out for a group stage ticket from 12 yards.
Gerrard's team were made to rehearse their chosen spot-kick ahead of Thursday's second leg at Ibrox but the Light Blues boss confessed: "I don't think it's a big advantage because it's a completely different situation.
"Taking a penalty in front of 22 players and 10 members of staff is not the same as doing it in front of 47,000.
"It's very difficult to replicate that situation but I do think walking up, preparing your technique and having a think about where so you're putting the ball so you're really set in your decision before the penalties come can be helpful, so that's the reason behind it."
Gerrard has also urged his side to keep their cool as they look to see off Legia, who would leave Gers having to score at least twice should they grab an away goal in Govan.
He said: "We want to be as aggressive as possible. We want to avoid conceding an away goal, of course we do. But we also have to prepare for setbacks within the game and if things take a turn for the worst.
"I don't want to see a negative reaction if that is the case. We want to play this game with confidence and belief.
"We have got a decent record at Ibrox. It's not the nicest place to come to for opposition players and teams.
"We expect the fans to be right up for this one. We expect the place to be rocking. We want to give them a performance that suits that atmosphere."